DE69732234T2 - WOVEN FABRICS OF HIGH E-MODULE MATERIAL - Google Patents

Abstract

The present invention is directed towards yarns of covered high modulus filament materials and fabrics which are formed therefrom. The present invention is intended to provide a composite filamentary material which exhibits the advantages of high modulus materials while providing a means for compensating the diminished properties exhibited by such fibers in the direction normal to molecular chain orientation. The composite filament structure of the present invention is a high modulus filament material covered with bicomponent filaments. The composite filament structure has a first interior layer of high modulus filament material and a second exterior layer of bicomponent fibers, the second exterior layer of bicomponent fibers being covered around the first interior layer of high modulus material along its entire length. The entire surface area of the high modulus material should be covered.

Description

Territory of invention

The The present invention relates to fabrics made of high modulus materials consist, for example, of polymeric materials in one second material are covered. The fabrics can be used in cloths for paper machines and in other industrial fabric applications be used.

background the invention

Paper machine clothing is the expression for Industrial fabrics used in paper machines in the wire, press and Drying sections are used. These are usually either with polyester or polyamide multifilaments and / or with conventional, huge looms woven monofilaments. These tissues are usually with conventional Web techniques have been produced.

The most important function of all paper machine search is the Extract paper sheet of water. Because both the manufacturers of paper machines as well as the paper manufacturers are eager to speed the paper making process and to improve paper quality new performance limits for Paper machine search revealed an innovation in the materials and in the design of tissues require. In addition, the paper machine manufacturer endeavoring to fabric for Make paper machine more efficient and important quality features to improve it.

today Paper machines achieve such high speeds that the Thickness of the tissue structure begins to limit the water withdrawal rate, especially in the wire section. Inadequate drainage leads to low strength of the paper sheet. The strength of the bow is important for the handover and maintaining the properties of the paper sheet in the next, more aggressive steps of bow drainage. One possible solution is the extension the wire section of the machine, however, this is quite expensive and therefore of limited practicability and prospects of success. The other approach is to that the manufacturer of paper machines manufactures thinner fabrics, however, are in a weaving process, the smallest possible dimensions are the combined ones Diameter of the used in the warp and in the weft direction Filaments. Criteria such as dimensional stability, fabric strength and tissue life to a practical limitation of the fineness of the filament diameter and thus the total thickness of the fabric. In numerous places the Paper machine is not a compromise on these properties feasible or not feasible, and indeed require higher Machine speeds further improve these properties.

It there is an absolute need for high strength, one lower weight, relatively thinner towels as the present available.

The surface topography of paper machine fabrics to the quality of the paper product. Efforts have been made to a smoother contact area to create with the paper sheet. However, the surface smoothness of Paper machine tissue limited by the topography, resulting from the Weave pattern and the physical features of the filament results. at a fabric (or a knit) is the smoothness through the fabric or knit even by those at the crossroads of the intersecting Yarns trained knuckles limited. High modulus materials are potential materials for use in application cases, where high mechanical properties and low weight required are. In terms of properties and weight have high modulus Polymers have a decisive advantage over metals and ceramics.

high modulus Polymers are highly anisotropic and have a high elastic modulus becomes only in the molecular chain direction reached. In fact, properties perpendicular to the molecular axis are considerably lower Values on than those in the longitudinal direction festzustellenden. As a result, in the direction perpendicular to the molecular axis to detect lower shear and pressure characteristics.

In the prior art composite concepts are known to compensate for the deviations in properties. The representative US Pat. No. 4,927,698 discloses yarns of a core of fire-resistant filaments such as Kevlar ^® or Nomex ^®, in a sheath of shrinkable staple fibers such as made from yarn, the cross-linkable with the fire-resistant core through reactions between a first Resin, the Kevlar ^® / Nomex ^® component and the staple fiber component seem to be chemically bonded.

From the published on 8 April 1997 US 5,617,903 Furthermore, a paper machine fabric is known, which consists of polymer fibers with a proportion of 15 percent or more of fibers greater than 100 denier and multipolymer fibers. The multipolymeric fibers contain two or more distinct polymeric regions in their cross-sections. The multipolymeric fibers may be in a sheath-core arrangement, side by side or in In be made in the flow form. The components of the multipolymeric fibers are each selected to provide a combination of properties that are not available from a single polymer fiber.

Summary the invention

The The present invention relates to fabric according to claim 1 consisting of yarns Covered high modulus thread materials are formed. The present The invention is intended to provide a composite thread material which has the advantages has high modulus materials and at the same time a means to compensate for the reduced properties of such fibers in the direction perpendicular to the molecular chain alignment, provides.

The The present invention is a composite yarn structure wherein a high modulus Thread material is covered with two-component monofilaments. The composite thread structure has a first inner layer of high modulus thread material and a second outer layer made of bicomponent fibers, wherein the second outer layer of bicomponent fibers around the first inner layer of high modulus material over the whole length is covered. The entire surface of the high-modulus material must be covered.

The Two-component fibers of the present invention may be either a sheath-core arrangement or a juxtaposed arrangement, wherein the sheath-core arrangement is preferred. Furthermore, the sheath component should preferably have a melting point lower than that of the core component is. Suitable bicomponent fibers include sheath-core combinations copolyester / poly (ethylene terephthalate), polyamide / poly (ethylene terephthalate), Polypropylene / poly (ethylene terephthalate), polyethylene / polyamide, polypropylene / polyamide, thermoplastic polyurethane / polyamide and thermoplastic polyurethane / poly (ethylene terephthalate).

at As used herein, "modulus" refers to tensile modulus as defined by the slope of the first linear portion of the stress-strain characteristic (of Stress-strain diagram) of a deformed at room temperature Specimen.

at As used herein, high modulus material includes high modulus polymers, which is an e-module for Tensile stress of theoretically greater than 25%. alternative a high-modulus polymer is a polymer that has an e-modulus for tensile load from bigger than has about 25 GPA. Encyclopedia of Polymer Science (Encyclopedia of Polymer Science), 2nd edition, Volume 7, pp. 699-722. It should be noted that highly oriented polymer structures are anisotropic, and that the modulus is increased by the degree of Molecular chain orientation elevated becomes; the module decreases in other directions accordingly.

Suitable high modulus polymers include aramids, such as poly (p-phenylene terephthalamide), available from Dupont under the tradename Kevlar ^®, other aramids such as KERMEL ^® (available from Rhone-Poulenc), Arenka ^®, available from Akzo, Nomex (available from DuPont), polyethylene naphthalate (PEN), poly (p-phenylene benzobisthiazole), polyesters, glass, aromatic polyamide resins Arenka ^®, a product available from Akzo aramid, thermotropic copolyesters such as Vectra ^® (Celanese ) or Xydar ^® (Dart), high modulus polyethylene fibers such as Spectra 900 (Allied).

the One of ordinary skill in the art will be aware that there are several options where the high-tech interior can be covered, such as for example Braiding and wrapping. A braid of bicomponent fibers around the highly modular interior provides a structure with good stability. The wrapping of the high modulus fibers with the bicomponent fiber material is another suitable method. Fibers can work with a single rewinding machine or with a double rewinding machine to be covered. In both cases the core fibers are spirally covered at a selected pitch.

at The production of fibers of the present invention will be advantageous exploited the unique structure of Zweikomponentenfilament. Of the Melting point of the sheath component is lower than the melting point of the highly modular interior. An improved structural integrity is achieved by Heat of the fabric that has been formed from the yarns that are themselves overlap each other in the tissue, to a temperature above the melting point of the shell and below the melting point of the core and the highly modular interior, followed by subsequent cooling, awarded. This method, hereinafter referred to as heat fusion is designated, causes the sheath components of the bicomponent fibers go into a softened state, and accordingly, the yarns fuse together at points of contact, when at temperatures below the melting temperature of the cladding material chilled become. Mostly these points of contact are the points where the yarns intersect each other.

Due to the improved stability of the fabrics of the present invention, it is expected that a single-ply fabric made from the composite yarns of the present invention can be successfully run in a paper machine. That is, the present invention provides a means for producing single-ply fabrics capable of withstanding the rigorous conditions experienced by papermaking fabrics. Typically, fabrics must consist of at least two layers to ensure that the fabrics have the necessary dimensional stability and strength to withstand the demanding operating conditions.

The The present invention may also be used as the top laminate structure a multilayer structure are used, and it is expected that their use as such a layer due to the lower Size of the ankles up the surface the fabric and the smaller thickness of the fabric advantages over conventional Materials will offer. The reduced size of the ankle creates a smoother tissue surface, a Feature that is desired by the paper makers. It is still possible, using the high modulus composite yarns of the present invention a thinner one Fabric because the excellent tensile properties of High-modulus materials mean that less material is used can be to achieve the strength, the conventional Have tissue. The present invention may also be used as the carrier layer a multilayer structure can be used. The improved dimensional stability and dimensional accuracy This layer makes it well suited for this application. The usage a fabric according to the invention as a carrier layer will give certain benefits to the overall fabric construction. Because the Composite yarns of the present invention along a relatively high strength the axis of the yarn represents the use of this fabric layer as a carrier layer the stability and the strength required by the overall fabric structure become. Therefore, you can less rigid materials used in other fabric layers so that the paper maker for example fibers a fine Deniers can choose to make other layers. Accordingly can Tissue can also be made thinner in this way. A thinner tissue is desirable because of this the drainage properties would be improved.

The Yarns can the only constituents of at least one layer of cloth be. In the case of a multi-layered cloth, at least a layer of the yarns of the present invention, and preferably set the surface layer in contact with the paper sheet independent of whether the tissue is a monolayer or a monolayer multi-layered fabric, the bicomponent fibers are neat and not by chance to arrange. By neat, non-random arrangement is meant that fibers of a blanket extend in a first direction, wherein the fibers running in the first direction do not interfere with each other in the first direction running fibers overlap, and that fibers of the cloth in a second direction, wherein the in the second direction fibers do not interfere with others in the second direction running fibers overlap that in the first direction extending fibers with in the second direction intersecting fibers and vice versa. For example, overlap fibers arranged in the machine direction are not mutually exclusive, but they overlap only with fibers that run in the cross-machine direction.

The Cloth can consist of fibers in the machine direction or in the cross-machine direction run, however, can The cloths also consist of fibers that are in directions at angles to the machine direction or the cross machine direction of a paper machine run.

Short description the drawings

1 is a composite braid of the present invention.

2 is another composite braid of the present invention.

3 is a cross section of a yarn of the present invention.

Full Description of the preferred embodiment

1 is a fabric made of yarns of the present invention. The fabric is a base weave structure wherein the yarns in the warp and weft directions are yarns of the present invention. Out 1 It can be seen that the yarns are connected to other yarns at the points where the yarns overlap. This is due to the heat fusion of the yarns, with the sheaths of the bicomponent materials being fused together after the fabric has been heated to a temperature above the melting point of the sheath material and below the melting point of the core material.

In the 1 The yarns of the fabric shown in the warp direction and the yarns of the fabric in the weft direction are of the same structure. The high modulus interior of the yarns are about 134 filaments of Kevlar ^® 49. Eight bicomponent yarns have been braided around the interior of Kevlar ^®. each Yarn consists of sixteen two-component monofilaments. The monofilaments are Bellcouple ^® from Kanebo, 250 denier, yarn number 16, with a low-melting copolyester sheath material and a poly (ethylene terephthalate) core, wherein the melting point of the Copolyestermantels is lower than the melting point of the polyethylene terephthalate core (PET core).

The eight two-component yarns are braided around the interior of ^Kevlar® . Lichen forms a relatively stable structure, and the covered high modulus yarns can be used to knit fabrics as in 1 shown train. Such fabrics are formed by methods well known to those of ordinary skill in the art. After the web has been formed, it is tensioned, heated to a temperature above the melting point of the jacket and below the melting point of the core, and thereafter cooled to a temperature below the melting point of the jacket.

by virtue of the improved stability The fabric of the present invention is expected to have a single-layer composite yarn of the present invention Fabric can successfully run on a paper machine. That means, that the present invention provides a means for producing single-ply Provides tissue that can withstand demanding conditions can, those paper machine cloths be subjected.

Usually have to Fabric consist of at least two layers to ensure that the fabrics have the necessary dimensional stability and strength, to withstand the demanding operating conditions. That I however, the papermaker's fabric of the present invention Materials with a high elastic modulus and low elongation characterized, rigidity and dimensional stability of the fabric is through provided the layer of high modulus materials, and accordingly Single-layer fabrics are possible. In other words, it is due to the great strength of such Materials provided, possible, less material to use the production of a fabric and at the same time a To provide strength equal to or greater than that of multilayer materials is that contain much more material. A single-layer fabric to achieve that would be a major breakthrough in development and manufacturing of paper machine stuff. As the machine speed increases, which is the time for Drainage reduced It is becoming increasingly important to achieve the smallest possible thickness since a single-layer fabric thinner is as a multi-layered tissue, which reduces the distance is going to cover a liquid has to be drained to become.

The The present invention may further be referred to as the upper laminate structure a multilayer structure can be used, and it is expected that their use as such a layer due to the greater flatness on the surface Advantages over usual Will provide materials. Increased flatness is the result the reduced size of the ankles the points where the yarns overlap. In the heat fusion of the fabric breaks the component of the bicomponent fiber with low Melting point and flows, so that the size of the ankles is reduced to the crossing points.

The present invention may further be used as the base layer of a multi-layered structure. The improved dimensional stability of this layer makes it seem well suited for this type of use. Thus, other materials, such as those with a small diameter, can be used in other layers since stability and strength are introduced by the layer of high modulus material. The use of small diameter materials in layers that come into contact with paper sheets would improve surface smoothness, which is a desirable feature of papermachine paper. 2 shows a tissue, with respect to 1 yarns described above are used in the warp direction. The yarns of the weft direction consist of nine-ply material. That is, they are a layer of nine yarns of bicomponent material as described in FIG 1 , The multiple yarns are loosely twisted. The yarns have a distinguishably flat appearance. That is, after the heat fusion, the yarns assume a band-like appearance.

3 shows a cross section of a composite yarn according to the present invention. The interior of Kevlar ^® is visible as a distinguishable area. The two-component exterior is not discreet.

When running on a paper machine, it is expected that a fabric according to the present invention will remain cleaner than a cloth made of conventional monofilaments. Heat fusion of a bicomponent fiber fabric is partially characterized by melted, overcut yarns. In contrast, conventional monofilaments have spaces at points where yarns overlap. Gaps are pinch points where contaminants can be trapped and accumulated over time. Accordingly, the interlaced heat-fused yarns made of bicomponent fibers provide a structure from which to expect It is that it will remain relatively cleaner than a conventional monofilament cloth.

One Another advantage of paper machine of the present Invention over conventional from monofilaments existing cloth is expected that such cloth the overlap points a relatively flat, ankle-free surface exhibit. It will be obvious and recognizable that if Fibers are woven (or knitted), knuckles are formed reduce the surface smoothness. As already noted, the ankle size becomes heat-fusion of the bicomponent fibers reduces what improves the surface smoothness. The surface smoothness is a factor affecting paper quality affected. Accordingly, cloths with improved smoothness of interest in the manufacturer of paper and related products. With heat fusion A cloth made of bicomponent fibers becomes a net of bonds between overlapping ones Fibers formed. Physical bonding of this type becomes the dimensional stability across from usual from monofilaments improve existing cloths. Due to the nature of the bicomponent fibers and the unique structures that they can form can be fibers be used with lower denier than that for conventional monofilaments is required. The use of lower denier fibers offers the advantage of a thinner one Tuches as a cloth that consists of conventional monofilaments, without that this is at the expense of fabric strength.

Claims (13)

Fabric for use in screening, pressing and the dryer section of a paper machine, the fabric being at least has a layer that consists of a composite yarn that consists out: a first yarn of high modulus thread material in one second yarn; wherein the second yarn is a bicomponent thread material is the two-component thread material, a sheath component as well has a core component and the bicomponent thread material the first high-modulus thread material covered and the first high-modulus Thread material over the length of the Wrapped in composite yarn. The fabric of claim 1, wherein the yarns containing the Forming tissue, being woven. The fabric of claim 1, wherein the yarns containing the Form tissue, are knitted. The fabric of claim 1, wherein the composite yarns extend in the warp and weft directions. The fabric of claim 1, wherein the composite yarns extend in the warp direction. The fabric of claim 1, wherein the composite yarns extend in the weft direction. The fabric of claim 1, wherein the first high modulus Material is selected from the group, made of high-modulus polyamides, aramids, polyethylene naphthalate, Glass fiber, thermotropic aromatic copolyesters, poly (p-phenylbenzobisthiazole), Polyesters and high modulus polyethylene fibers and blends thereof consists. The fabric of claim 1, wherein the sheath-core combinations the bicomponent fibers of copolyester / polyethylene terephthalate combinations, Polyamide / polyethylene terephthalate, polyamide / polyamide, polyethylene / polyethylene terephthalate, Polypropylene / polyethylene terephthalate, polyethylene / polyamide, polypropylene / polyamide, Thermoplastic polyurethane / polyamide and thermoplastic polyurethane / polyethylene terephthalate selected become. The fabric of claim 1, wherein the high modulus thread material Furthermore, it consists of a large number of high-modulus monofilaments. The fabric of claim 1, wherein the bicomponent suture material further consists of a plurality of two-component yarns and each bicomponent yarn further comprises two-component monofilaments a sheath-core arrangement exists. The tissue of claim 1, wherein the tissue is applied to a Temperature over the melting point of the shell component, but below the melting point of Core component is heated and to a temperature below the melting point cooled the jacket component becomes. The fabric of claim 1, wherein the composite yarn is present the production of the fabric heat-melted becomes. The tissue of claim 1, wherein the tissue is a monolayer Tissue is.